High speed braking stability

[ikbenben]

Why not?! I want one ... especially one of those big bumper mount ones ...

Because I like to keep it subtle...don't like big wings if they're not standard.

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[BarracksSi]

I'll have it checked. Still I find it weird that it wouldn't be correct from the factory.

In another thread, where they were talking about how often cars are semi-abused being driven on and off ships and trucks between the factory and the dealer, plus how they're strapped down to keep them from wrecking each other, ...

I remarked that it's amazing that they drive straight at all by the time we buy them.

 

[aydingokce]

I also have a similar problem. When I brake at high speed, if the car is going in a straight line, the only problem is, it does not give me confidence, it just feels loose and unstable, but no big deal. The actual problem is when going through a curve. When I am negotiating a curve at, say, >160 km/h, if I have to touch the brakes, the car deviates from the lane significantly, in addition to feeling loose and unstable. On one occasion, I tried to correct this behaviour with steering and the car started to sway wildly, it was really a nightmare! By the way, when I say negotiating a curve at >160 km/h, I do not necessarily mean that the curve is tight. It also happens when the curve's radius is big enough to go through it at >160 km/h without experiencing high lateral acceleration.

Does it have to do with the wheel alignments, as it is said above? Should I install a rear sway bar?

 

[BarracksSi]

Should I install a rear sway bar?

I wouldn't change to a stiffer rear sway as it'll change the handling balance to more neutral (closer to being tail-happy) than it is now. Nobody needs a stiffer rear swaybar for street driving; it helps the car rotate through corners, while you want more stability.

I'd check alignment, and if that doesn't help, I'd also consider a rear wing (yes, really). I'll probably never get to drive my FK as fast as you've taken yours, but I'm pretty sure a little downforce (and rear-biased aero drag) would go a long way.

HOWEVER, as I think about what you wrote...

I'm not so sure it's a great idea to correct the car's mid-corner attitude at those speeds by using the steering. Throttle modulation should be enough.

How do other cars compare at similar speeds on the same route? Have you got some experience on-track (or someplace where, if you actually lose control, you probably won't die)?

 

[totopo]

I also have a similar problem. When I brake at high speed, if the car is going in a straight line, the only problem is, it does not give me confidence, it just feels loose and unstable, but no big deal. The actual problem is when going through a curve. When I am negotiating a curve at, say, >160 km/h, if I have to touch the brakes, the car deviates from the lane significantly, in addition to feeling loose and unstable. On one occasion, I tried to correct this behaviour with steering and the car started to sway wildly, it was really a nightmare! By the way, when I say negotiating a curve at >160 km/h, I do not necessarily mean that the curve is tight. It also happens when the curve's radius is big enough to go through it at >160 km/h without experiencing high lateral acceleration.

Does it have to do with the wheel alignments, as it is said above? Should I install a rear sway bar?

Honestly, you are kind of lucky the car has all these fancy traction control safety things, or you had/have a really high chance of wrecking your car and/or your life. I honestly hope you were at a racetrack, but I suspect not since your most likely mandatory instructor would have bitten your head off for thinking of braking in the middle of a turn at 160 km/h.

I think these cars are pretty neutrally tuned compared to historic fwd cars for the driving dynamics, which means there is less margin for safety. Braking in the middle of any turn is a big no-no for street driving and for racing. brakes are really strong and tires have a lot of traction in the vertical direction. This equates to huge weight shifts to the front of the car, which means no weight on the rear, which means pretty drastic oversteer, even if you previously were nowhere near the edge of your traction circle. By no means should you increase the rear sway bar, it will make everything even worse.

If you are at the edge of your traction circle, even lifting off the gas is a no-no and can cause oversteer at high speeds, especially with the extra rear lift at speed.

Why are you even braking in a turn at 160 km/h? should never have to happen. That's why you don't drive recklessly on the street if you can't control what other people do.

There are so few options when you overspeed into a corner. Remember the mantra, slow in, fast out.

Alignment can be an issue. More toe in on the rears makes the car more stable in braking. It will still wiggle around, but it will self correct and stay straight.

Shock rates can also affect hopping and stability on braking, but there really isn't a good solution yet for the civic.

 

[aydingokce]

Thank you for the replies. Basically, there are two questions that need to be answered, so please let me do so:

1) Where and where are you going that fast?

I wish it were on a track but unfortunately no, I was mentioning about highway driving. It may look crazy, but, in my country, where the society generally adopts the principle "rules are meant to be broken", it is just a normal action. I do not want to be misunderstood, when I say normal action, I mean statistically normal action, not a right / correct / legitimate one. In our highways, when you stick to the legal speed limits, you will see hundreds of cars overtaking you every hour. When virtually everybody do something and benefit themselves, even if it is not right / correct / legitimate, you also feel the urge to do it. This is just human nature.

2) Why are you braking when going through a corner at such a high speed?

Of course it is not my preference. We also have tons of idiot drivers, which are not capable of following their lanes when going through a corner even at a slow speed. They just suddenly drive their cars into my lane FOR NO REASON (oh yes, there is a reason, they are not capable of holding the steering wheel in a correct position when going through a corner) and cause me to brake.

By the way, I was not mentioning about hard braking. Only touching the brakes a bit.

 

[totopo]

Thank you for the replies. Basically, there are two questions that need to be answered, so please let me do so:

1) Where and where are you going that fast?

I wish it were on a track but unfortunately no, I was mentioning about highway driving. It may look crazy, but, in my country, where the society generally adopts the principle "rules are meant to be broken", it is just a normal action. I do not want to be misunderstood, when I say normal action, I mean statistically normal action, not a right / correct / legitimate one. In our highways, when you stick to the legal speed limits, you will see hundreds of cars overtaking you every hour. When virtually everybody do something and benefit themselves, even if it is not right / correct / legitimate, you also feel the urge to do it. This is just human nature.

2) Why are you braking when going through a corner at such a high speed?

Of course it is not my preference. We also have tons of idiot drivers, which are not capable of following their lanes when going through a corner even at a slow speed. They just suddenly drive their cars into my lane FOR NO REASON (oh yes, there is a reason, they are not capable of holding the steering wheel in a correct position when going through a corner) and cause me to brake.

By the way, I was not mentioning about hard braking. Only touching the brakes a bit.

all right, i'll consider it cultural differences and give my advice

- Never ever turn off your traction control. The oem brake control should help straighten out your car during braking. Never turn it off on the street.

- IF you want to continue driving the way you do, I would STRONGLY suggest better tires. Like at LEAST Max performance grade if not extreme performance summer grade. Better tires means more lateral traction is available until you lose control.

- You should drive as much as possible under the assumption that you CANNOT brake and turn at the same time. Get used to watching the cars far ahead of you and predicting your spacing and leaving enough room in case they are retarded. Brake before you start turning your wheel. The fact that you even have to brake shows to me that you are trying to go through turns faster than other people. Just go with the flow and go faster on straights and slower through turns. There is no need to prove yourself and go faster than the surrounding traffic.

- People fail to appreciate how unsteady the car gets at higher speed, like especially the autoX guys. Things that will barely upset the car at 40 km/h will wreck your car at 160 km/h. You have to be gentle with all your inputs at speed. Yes, you may be only tapping your brakes, but when you are at like 160 km/h zone, even lifting off the gas pedal can mean loss of control. Tapping your brakes at 120 km/h is uncomfortable. Tapping your brakes at 160 km/h is asking for trouble.

- At this point in time there are very few suspension mods that will help you. If anything it would be to remove your rear anti-sway bar.

It basically sounds to me like you are asking your car to break the laws of physics, and that just can't be done. Buy a GT-R or porsche GT4 if you want to bully people with insane traction on the streets.

 

[BarracksSi]

I'd like to know Turkey's accident statistics now...

Okay, let's unpack this for a minute --

Both the OP from Belgium, ikbenben, and our Turkish colleague, aydingokce, report that heavy braking from high speed in a straight line feels unstable.

This could be an alignment problem (just because the car is factory fresh doesn't mean that its alignment couldn't be improved).

It may be an aero problem, but only while the car is traveling fast enough for the aerodynamics to have any effect.

Could it be a brake balance issue? I'd expect not, as I'm sure Honda's done their homework on the braking.

--------
Tangential topic:

Sudden braking in a corner is a no-no, true; moderate braking might be bad, but it kinda depends on the radius of the corner, too. If it really is a long, easy, large-radius corner, and you're nowhere near the limit of adhesion, and you don't shift the weight of the car too much, maybe it'll stay steady.

Take this thought with a grain of salt, though; as totopo said, us autocross guys don't usually learn what a car does at high speed (the rule book requires courses to be designed to keep cars at US-legal highway speeds or below).

aydingokce, have other cars of yours behaved the same way under similar conditions?

Quick bit about speeding-as-a-cultural-phenomenon: I'm of the mind that going with the flow is safer, like if the posted speed limit is 55 but everyone's going 75, I'll go 75 with them (likewise, if the speed limit's 55 and everyone's going 20, I'm going 20, too). I don't know what the national speed limit in Turkey is, but it doesn't sound like the populace is abiding by any rules, either -- so now I'm wondering if there's usually a large speed differential between the slowest and the fastest drivers.

 

[ronmcdon]

Cultural norms are no excuse for reckless driving.

 

[aydingokce]

Thank you for the replies all. As I previously said, this happens with a gentle braking when I am nowhere near the limit of adhesion in the curve. Speed may appear large but the curve is also large. I have done some amount of spirited driving on my F20 1.16i with a standart suspension setting (whose level of grip in the curves is, I believe, no match for my new Civic), I did not notice a similar issue. By the way, it was indeed not so stable in curves. When I went over a slight bump within the corner, It was losing it stability. No such issue in the Civic. But, it was much stable in in - corner braking.

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